1) Field of the Invention
This invention relates to a chemical heat pump and more particularly to a chemical heat pump for working at any desired working temperature, which is suitable for process heating, generation of steam and hot water, room heating, hot water supply, etc. and can be used for utilizing midnight electric power, waste heat, etc. including the so called cogeneration.
2) Description of the Prior Art
A chemical heat pump of closed CaO/Ca(OH).sub.2 system utilizing reversible reactions between the reaction of calcium oxide (CaO) with water to form calcium hydroxide [Ca(OH).sub.2 ] and the reaction to dehydrate calcium hydroxide to calcium oxide and water is disclosed, for example, in Japanese Patent Application Kokai (Laid-open) No. 61-180891.
That is, in a closed system where an evaporator-condenser is in connection with a reactor, that is, a regenerator-heat releaser, CaO is filled in the reactor, and the evaporator-condenser and the reactor each have a heat transfer tube at the inside. When a cooling medium is passed through the heat transfer tube of the evaporator-condenser and a regenerating heating medium is passed through the heat transfer tube of the reactor, the pressure in the evaporator-condenser reaches the water vapor pressure at the cooling medium temperature, that is, vacuum, and Ca(OH).sub.2 in the reactor is heated up to the regeneration temperature in vacuum to regenerate Ca(OH).sub.2 to CaO. The water vapor generated in the reactor is condensed to water in the evaporator-condensor.
When the regenerating heating medium is passed through the heat transfer tube in the evaporator-condenser after the regeneration, water is evaporated and the pressure of the evaporator-condenser is elevated to the water vapor pressure at the temperature of the regenerating heating medium and the resulting water vapor reacts with CaO in the reactor and the regenerating medium at an elevated temperature can be obtained from the heat transfer tube of the reactor.
In the above-mentioned prior art, the working temperature of a heat pump depends upon a working pressure, that is, water vapor pressures at the regeneration temperature and the cooling temperature, and no consideration is given to the fact that the working temperature of a heat pump cannot be changed.